1. Field of the Invention
The present invention relates to a capsule for dental restoration material, which can be administered to a site to be restored of a patient, immediately after mixing a dental restoration material comprising two components of definite amounts of previously weighed powder component and liquid component, for filling, cementing, lining and other applications for restoration of a tooth in the dental remedy field, and in a good state where the mixture does not substantially contain air bubbles.
2. Description of the Conventional Art
In general, a dental restoration material is used for restoration of a tooth, such as filling, cementing and lining. As the dental restoration material, a two-component system material comprising a powder component and a liquid component, which are reacted with each other upon mixing, is usually used. Hitherto, this two-component system dental restoration material was provided for use after appropriately weighing the powder component and the liquid component every time and mixing them with each other. However, in recent years, for the purposes of omitting a weighing operation of the powder component and the liquid component and an operation for accommodating the dental restoration material after mixing into a syringe for administering it to a site to be restored, there have been developed capsules for dental restoration material, in which definite amounts of the powder component and the liquid component are previously weighed and accommodated in an isolated state from each other, the isolated state is released at a desired time, the both components are mixed with each other by mechanical shaking in a mixer, and the resulting mixture is extruded and administered directly to a site to be restored, such as a tooth cavity, through a nozzle.
For example, in a capsule as disclosed in Japanese Patent Publication No. 38853/1991, a powder component of two components is accommodated in a mixing compartment of a capsule main body, and the other liquid component is charged in a bag (pillow) formed by a sheet film, which is assembled in a side portion of the mixing compartment accommodating the powder component by means of a clip. The capsule main body has an outlet hole in a front end portion thereof. This outlet hole can be clogged in a cylindrical bearing portion in a rear end portion of a nozzle. Further, the nozzle is kept from the outside by means of a separately formed cap, thereby preventing the powder component from leakage out of the mixing compartment. And, at the time of use, the clip is pushed toward a direction of the mixing compartment, thereby smashing and breaking the pillow accommodating the liquid component therein; the liquid component is made flow into an interior of the mixing compartment through an aperture provided on a side wall of the mixing compartment, followed by shaking in a mixer to mix the liquid component and the powder component with each other; the cylindrical bearing portion in the rear end portion of the nozzle is then rotated to release a passage of the nozzle; and a plunger is pushed by means of a push rod of a separately prepared applier to extrude the mixture through the nozzle.
Further, in a two-component system capsule for mixing and discharge as disclosed in Japanese Patent Laid-Open No. 268555/1987, a powder component of two components is accommodated in a mixing compartment within a capsule main body, and the other liquid component is accommodated in a bag (pillow) formed by a sheet film comprising a resin, a metal foil, or a laminate of a resin and a metal foil. In this pillow, the strength in the main body side is previously set to be low, and the pillow is assembled by a cap to be screw engaged with the capsule main body in the front end side of the capsule main body. At the time of use, when the cap is strongly screw engaged with the capsule main body and moved, the pillow is ruptured, the sheet in the capsule main body side is broken, and the liquid component flows into the mixing compartment through an outlet hole provided on a center axis of the front end of the capsule main body. Thus, when shaking is performed in a mixer, the liquid component is mixed with the powder component. After mixing, a through rod set within a nozzle provided on a center axis of the cap is pushed in and breaks through the sheet of the pillow in the cap side, i.e., in the nozzle side, to form a discharge outlet for the mixture. Thereafter, the through rod is removed, a plunger set in an interior of the rear end portion of the capsule main body is moved into the side of the front end portion of the capsule main body by a push rod of an applier, and the mixture in the mixing compartment is discharged through the nozzle.
Further, like Japanese Patent Laid-Open No. 268555/1987 as cited above, Japanese Patent Publication No. 81384/1991 discloses a capsule for dental restoration material in which a bag (pillow) having a liquid component accommodated therein, which is formed by a sheet film such as an aluminum foil, is aligned in an outside of a front end of a mixing compartment of a capsule main body; and the pillow is ruptured by a screw-in pushing pressure of a cap, thereby making the liquid component flow into the mixing compartment through an outlet hole on a center axis of the capsule main body. Thus, when shaking is performed in a mixer, the liquid component is mixed with the powder component. After mixing, a plunger having a pillow breakthrough body provided in a rear end portion of the capsule main body is moved by means of a push rod of an applier, to break through a front end of the pillow in the nozzle side, thereby extruding the mixture within the mixing compartment.
Each of the above-described capsules used a pillow in which the liquid component is wrapped by a sheet film using a metal foil or the like. As a capsule in a mode not using such a pillow, Japanese Patent Laid-Open No. 131459/1996 discloses a capsule having a structure comprising a cylindrical capsule main body having a mixing compartment for accommodating a powder component therein, in which a thin film-like seal portion for clogging a circular outlet hole for a mixture, which is provided on a center axis of a front end portion, is formed, a male screw is screw provided on an outer periphery side surface from a front end portion to a center portion, and an applier-engaging groove is engraved on an outer periphery side surface in the vicinity of a rear end portion; a cup-like liquid-accommodating tool for accommodating a liquid component therein, in which a thin film-like seal portion forming a circular flow-in hole for the liquid component is formed on a center axis of a front end portion thereof, an evagination portion that is embedded in a cylindrical portion for forming the mixing compartment of the capsule main body is provided on an outer periphery surface in the vicinity of the front end portion, and a convex stopper having a size such that it does not easily slide into the capsule main body during breaking through the thin film-like seal portion to form the flow-in hole for the liquid component, but, when a large force is applied, it is not inhibited to slide into the capsule main body, is provided on an outer side surface in the vicinity of a rear end portion thereof; a plunger, in which a tip portion thereof for breaking through the thin film-like seal portion of the liquid-accommodating tool and the thin film-like seal portion of the capsule main body has a planar rod-like protrusion in its front end portion, and an evagination portion that is embedded a cylindrical portion within the liquid-accommodating tool is provided on an outer side surface in the vicinity of the front end portion; a cap having a nozzle-engaging mouth on a center axis of a front end portion thereof and screw provided, on an inner periphery side surface thereof with a female screw to be screw engaged with the male screw that is screw provided on the capsule main body; and a nozzle having a shape such that a rear end portion thereof can be engaged with the outer surface of the front end portion of the capsule main body.
In the capsules having such various structures, when the dental restoration material comprising two components of definite amounts of the previously weighed powder component and liquid component as is mixed by shaking in a mixer, air present in the mixing compartment mingles into the mixture, whereby it exists as air bubbles. For this reason, the dental restoration material administered in a dental restoration site such as a cavity of a patient contains the air bubbles. Accordingly, the capsules of the conventional art involved various problems including a decrease in the strength and a change in the color tone with respect to the dental restoration material.
An object of the present invention is to overcome the above-described problems of the capsules for dental restoration material of the conventional art and provide a capsule for dental restoration material, which is free from the occurrence of a phenomenon wherein, when a dental restoration material comprising two components of definite amounts of previously weighed powder component and liquid component accommodated in a capsule for dental restoration material of the conventional art is mixed by shaking in a mixer, air present in a mixing compartment mingles as air bubbles into the mixture.
In order to achieve the above-described object, we, the present inventors made extensive and intensive investigations. As a result, it has been found that in a capsule for dental restoration material for directly administering to a restoration site of a tooth with a mixture prepared by subjecting a dental restoration material comprising two components of definite amounts of previously weighed powder component and liquid component accommodated in a cylindrical mixing compartment in an isolated state from each other to making the liquid component flow into the mixing compartment and mixing the both components, when an air-permeable filter that does not pass the powder component therethrough but can ventilate air within the mixing compartment into the outside of the mixing compartment is placed in at least a part of a peripheral wall of the mixing compartment, the capsule for dental restoration material is placed in a vacuum atmosphere before mixing the powder component and the liquid component, whereby the air within the mixing compartment can be sucked into the outside of the mixing compartment, leading to accomplishment of the invention.
Further, it has also been found that the air-permeable filter may be placed in at least one of a state where it is placed so as to clog a passage for the mixture, which connects a nozzle for directly administering the mixture to the restoration site of the tooth to the mixing compartment, a state where it is placed on a side wall of the mixing compartment, and a state where it is placed in a plunger extruding the mixture toward the nozzle for directly administering the mixture within the mixing compartment to the restoration site of the tooth; and that it is preferred that the air-permeable filter has a characteristic that an air flow rate is 0.1 to 1,000 L/minxc2x7cm2 in the case where the ventilation is carried out under the conditions that a pore size is 0.1 to 100 xcexcm, a thickness is 50 to 1,000 xcexcm, and a differential pressure of air at 25xc2x0 C. is 69 kPa.